<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <style>
        /* 默认态
            l
            v
            h
            a
        */
        .a1:link{
            color: red;
        }
        .a1:visited{
            color: purple;
        }
        .a1:hover{
            color: yellowgreen;
        }
        .a1:active{
            background-color: gray;
        }
        
        /* 2个 */
        .a3{
           color: red; 
        }
        .a3:hover{
            background-color: pink;
        }
    </style>
    <a href="http://www.baidu1.com">百度</a>
    <a class="a1" href="http://www.baidu2.com">百度2</a>
    <a class="a3" href="http://www.baidu3.com">百度2</a>
    <hr>
    <style>
        .box{
            background-color: pink;
            height: 100px;
        }
        /* 悬浮  hover 哈弗   */
        .box:hover{
            background-color: yellow;
        }
        .box:active{
            background-color: black;
        }
    </style>
    <div class="box"></div>
    <hr>
    <style>
        /* ul li{
            background-color: pink;
        } */
        ul li:first-child{
            color: blue;
        }
        ul li:last-child{
            color: purple;
        }
        ul li:nth-child(4){
            background-color: yellowgreen;
        }
        /* ul li:nth-child(2n+1){
            background-color: yellowgreen;
        } */
    </style>
    <ul>
        <li>1111</li>
        <li>22</li>
        <li>22</li>
        <li>aaaa</li>
        <li>22</li>
        <li>22</li>
        <li>333</li>
    </ul>
</body>
</html>